Overvoltage relay



Aug. 14, 1956 o. c. WALLEY ovERvoLTAGE RELAY 2 sheets-sheet 2 Filed April 22. 1955 FIG. 5

FIG. 7

FIG. 6,

INVENTOR. .OMAR C. WALLEY ATTORNEY United States OVERVLTAGE RELAY @man C. Walley, Cleveland, Ohio,- assignor to Jack & Hei'ut'z, Inc., Cleveland; 0lrio,.a1 corporation of Dela wareV Application April`22`, 1955Serial'No. 503,245

iClaims. (Cl. 200`122) The present. invention relates to voltage responsive switches or relays and, more particularly, to a. voltage responsive switch or relay of the gas discharge type suitable for use asan overvoltagefrelay in electric. current generating systems.

Over'voltage. relays are commonly used in aircraft alternating. current systems tti-perform' a switching function resulting in the cutting out of the generator. causing the overvoltage. A relay for use in this type of. system requires. a time delay in itsoperation upon the occurrence ofan overvoltage so as not to be operatedv by unobjectionf able transients inthe system. The relay should. also have aninverse time characteristic so that the delay in` the op.- eration of the contacts decreases' as the magnitudeof the overvoltage increases.

One of the important. objects of. the present invention is. to. provide a new and improved overvoltage relay in which. the overvoltage is determined by gas discharge means and in whichY there is atiirre delay in the operation ofthe relay upon the occurrence of an o-vervo-ltage, the duration of. the time delay normally decreasing. as the magnitude of the overvoltage increases.

Another object of the present invention is to provide an overvoltage relay or switch for aircraft electrical systerrr which is substantially independent of the variations offrequerrcy in the system and which is substantially unaifected by the wide range of operating temperatures to which. aircraft components are subjected.

Another object of the present invention is to provide a gas discharge or glow tube type thermal time delay relay in which the time delay is achieved by the thermal capacity of the parts and in which the contactsv are actuated" by a' member expanded in response to the heating effect of the gas discharge.

Another object of theA present invention, is to provide a new and improved gas discharge or glow tube type thermal time delay relay in' which the switching operation performed by the relayy isv in a circuit separate' from the electrical circuit for. establishing the gas discharge.

Another object of the present invention is to provide a new and improved gas discharge` or glowv tube type thermal time delay relay having a pair of cooperating contactsg. and in which only one of' the cooperating contacts issupported from or directly connected to` a contact actuating member expanded by the heating eect of the gas discharge to actuate they contacts and in which the support' for at least one of theV cooperating contacts inclrdes ambient' temperatureI responsive means', such as a biinet'al, whereby` the relay is rendered substantially independent of changesA in zunbientl temperature:

Another object of the present invention is to provide a new and improved relay, particularly a gas: discharge type. thermal time delay relay, in. which an elongated member is2 axially. expanded; by heating tol actuate. a pair o cooperating contacts supported: and? connected to the elongated member in auch a manne-r that. the; relay is.. inf henently. compensated for changesE in ambient tempera.- tures without the use: of special temperatur-e responsive 2 ,759,064 Patented.. Aug,` 14, 1956Y 2 devices, such, as bimetals, in the supporting means. for the contacts.

Another object of the present invention is toprovide a new and improved relay, particularly a gas discharge type thermal time` delay relay in. which an elongated member is heated. and axially expanded to a-ctuate a. pair of cooperating contacts supportedy adjacent to the elongated member by contact support members extending generally axially of. the` elongated member and. connect-ed to one end thereof. and otherwise so constructed and arranged that. the relay is inherently compensated for ambientl temperature changes without the use of special temperature responsive devices, such` as bimetals.

The present. invention resides in certain constructions and. combinations and arrangements of parts and further objects andadvantages thereof. will be apparent from the following. detailedl description of the preferred embodiment described with reference to the. accompanyingdrawings,.f orming.a partof this specification and in which:

Fignrel is a diagrammatic showing of a. generator circuit embodying a relay shownin section, which relay. embodies the present invention;

Figure. 2. is a View similar to Figurev l, but showing the contacts of. the relay in a. closed condition;

lEigure` 3-. is. a View similar to` Figure l showing the. eect of ambient temperature. on the contacts of the'relay;

Figures 4 and 5 are sectionaly views of, an overvoltage relay or. switch embodying an alternative form ofthe present, invention. respectively showing. the contacts of the relay in their open position and in their closed positiong.

Figure 6 is` asectionalv View taken along line 6--6 of Figure 4; and

Figure 7 is a sectional View taken along line 7 7v ot' Figure 5.

Referring to Figure l` of the drawing, an overvoltage relay 10. embodying the present invention is shown connected. into a circuit for energizing a relay coil. 11 of a cutout relay 12 in the held circuit of a generator 13. The overvoltage relay itl hasnormally openA contacts 14, 15 which when closedv complete a circuit energizing relay coil il to open the normally closed contacts. 16 of relay 12 in the eld circuit for the generator.

The overvoltage relay l@ comprises a closed tubular envelope i8', preferably of glass, or the like, closed at one end by a base member 2@ formed of insulative material, such as glass. The base member 2@ supports art-ubular member 2i' extending from the base member parallel to the axis of the envelope i8 and a member 22, preferably cylindrical which. extends coaxial with the tubular member 2l. The members 21, 22 are electrically conductive and are adapted to function as electrodes and will hereinafter be referred to as electrodes ZI, 22 respectively.

The upper end of electrode 2i is closed by a nonconducting member or cap 2id and the tubular electrode is lled with` an ionizable gas at a pressure suitable for supporting a gas discharge between the electrodes. 21, 212 at the voltage to which the relay is to be responsive.

The electrode 2 may be evacuated and filled with the ionizable gas in any conventional manner, such as by the use of an exhausting and filling tube, which is sealed'off after the proper gas pressure is reached. Electrical connections are made to the electrodes 21;,22'by ContactY pins 26, 27 connectedrespective'ly tothe electrodes 21, Z2 by lead-n wires2`. The contact pins 26,. 27 extend external'- ly ofthe support 2@ closing the base end of. the envelope I8 and' are connected with the output circuit of the generator so as to have a voltage applied thereto,` which a functionof the outputvoltage.

The. contact 14 of. the overvoltage. relay is supportedat the free endof a` contact supportmember 3l)v` depending from an overhanging portion 31 of the cap 24 which closes one end of the tubular electrode 21. The lower end of the member 30 is connected to the upper end of a rigid member or rod 32 mounted in the base member 20 by a strut 33 making acute angles with both the contact support member 39 and the rod 32 and forming a Z-shaped support for the contact 14.

The Contact 1S is supported adjacent to the contact 14 but in spaced relationship thereto, in the illustrated embodiment, by ambient temperature responsive means, preferably comprising a bimetallic support member 34 mounted in the insulative support 2G. The birnetallic support member 34 will move the contact 15 in a direction toward or away from the Contact in response to changes in ambient temperature to compensate for the change in position of tne contact 14, due to the effect of ambient temperature on the supporting members for contact 14, thereby maintaining a constant gap between the contacts 14 and 15. The operation of the bimetallic support member 34 may be seen by comparing Figures l and 3, which illustrate the normal open position of the contacts 14 and 15 under two diferent ambient temperature conditions. lt will be understood that ambient temperature responsive means can be incorporated into the support means for the contact 14 either instead of, or in addition to, the ambient temperature responsive means in the support means for contact 15, if so desired. Electrical connections are made to the contacts 14 and 15 through pins 35 and 36 extending externally of the base member and Connected to the rod 32 and bimetallic member 34 respectively, the rod 32 and strut 33 being electrically conductive.

In operation, when a predetermined voltage drop is established between the electrodes 21 and 22, the gas within the electrode 21 will ionize sufficiently to establish an electric current ow between the electrodes; in the relay illustrated, a glow discharge is established. The glow current heats the tubular electrode 21 causing it to expand axially which, in turn, causes the contact 14 to move toward the contact 15 through the action of contact support member 30 .and the strut 33. The contact support member 3G is moved lengthwise with the expansion of the tubular electrode 21, by reason of its connection thereto by the cap 24. Lengthwise movement of the contact support member 3ft by the cap 24 bends, or exes, the strut 34 about its point of connection to the rod 32, causing the contact 14 to move toward the contact 15.

The thermal capacity of the tubular electrode 21 will introduce a delay in the operation of the contacts after the glow current is established. The length of the time delay for a given relay will depend upon the magnitude of the glow current which in turn is dependent upon the t magnitude of the voltage applied to the electrodes 21 and 22. As the magnitude of the voltage increases the time delay in the operation of the contacts will decrease providing a quick operating relay when large over-voltages occur, but also providing n relay having a suflicient time delay so as not to be actuated by normal transients in the system.

From the foregoing, it may be seen the contacts 14, 15 are not affected directly by the glow discharge, or subject to the action of the ionizing gas, and only the contact 14 has a support member which is expanded by the heating effect of the discharge between the electrodes on the occurrence of an over-voltage. This enables the glow electrodes and the contacts 14 and 15 to be in separate electrical circuits land enables the gap between contacts 14 and 15 to be maintained constant in spite of Wide uctuations in ambient temperatures in the absence of a gas discharge between the electrodes 21 and 22.

In the form of the present invention illustrated in Figures 4-7 of the drawing, an overvoltage relay 40 generally comprises a tubular member or electrode 41 supported within an envelope 42 preferably evacuated and made of insulative material, such as glass, by the base 43 of the envelope. A rod-like member or electrode 44 is supported by the base 43 coaxially with the electrode 41 and the tit) space within the electrode 41 is filled with an ionizable gas at a suitable pressure for supporting a gas discharge, the top of the tubular electrode 41 being closed by non-conducting cap 45. Lead-in wires 46, 47 are each connected at one end to the electrodes 41, 44, respectively, and at the other end to pins 43, 49, respectively, supported by and extending outwardly of the base 43. The pins 4S and 49 provide means for making external electrical connection to the electrodes 41 and 44.

A bendabie or deformable band-like contact supporting member is connected between one side of the cap and the base 43. The contact supporting member 50 is electrically conducting and mounts a contact 51, preferably at the central portion of its length and is of such a length that it is normally in a bowed condition, as illustrated in Fig. 4. The contact 51 is 'adapted to engage a cooperating contact 52 supported by an electrically conducting ring-like contact support member 53. The ringlike member 53 encircles the tubular electrode 41 and is connected to and supported by a bendable or deformable band-like member 54- connected at one of its ends to the side of the cap 45 opposite the side to which the contact support member Sti is fastened and at the other end tothe base 43. The band-like member 54 is electrically conducting and is also of such a length that it is normally in a. bowed condition. External electrical connection to the contacts 51 and 52 is made through pins 55, 56 extending outwardly of the base 43 and respectively connected to the members 50, 54 by lead-in wires 57, 58.

In operation, the pins 55, :'56 are connected into a control circuit such as the circuit for relay 12 of Figure l and the pins and 49 are connected into the circuit which is to be protected against overvoltages, such as the output circuit of generator 13 of Figure l. When the voltage applied to pins 48 and 49 reaches a predetermined magnitude, the gas within the tubular electrode 41 will break down and a gas discharge will be established. The heating effect of the electrical current in the gas discharge causes the tubular electrode 41 to elongate, which in turn, straightens the bowed members 50, 54 to effect engagement of contact 51 with Contact 52, upon a predetermined elongation of the tubular electrode 41. The making of the contacts 51 and 52 completes a circuit between pin S5 and pin 56 to perform a control function. As in the first described embodiment, the contacts 51, 52 can be connected into an electrical circuit separate from the circuit for producing the gas discharge and are substantially uaffected by the discharge itself.

In the second-described embodiment, special ambient temperature responsive means is not required to conpensate for ambient temperature since the bowed members 50, 54 will be expanded or contracted in the same direction as the tubular electrode 41 by the effect of ambient temperature changes. Any differences in expansion due to the nature of the materials from which the tubular electrode and the band-like members are made may be compensated for by providing the proper material for the ring-like member 53.

While the preferred embodiment of the present invention has been described in considerable detail it will be understood that modifications may be made by those skilled in the art, such as breaking the contacts 14, 15 upon the occurrence of a gas discharge instead of making the contacts, and that it is my intention to hereby cover all such adaptations, modifications and arrangements falling within the ability of the skilled in the art to which the invention relates and the scope of the appended claims.

I claim:

l. In a relay, first and second cooperating contacts, means supporting said first contact for movement toward and away from said second contact, a first member in the form of a closed envelope that is expandable and contractible axially in response to temperature changes, means for establishing a gas discharge by ionizing the gas in the envelope independent of the making and breaking of said contacts in the presence of a gas discharge for heating said member upon the occurrence of a predetermined voltage condition and means interconnecting said first member and said first contact for moving said first contact to make or break said contacts upon the axial expansion or contraction of said first member in response to such gas discharge.

2. In a relay, first and second cooperating contacts, means supporting said first contact for movement toward and away from said second contact, a closed tubular member adapted to function as a first electrode, a second electrode within said tubular member, an ionizable gas within said tubular member, means for applying a difference of potential to said electrode to cause a gas discharge upon the application of a difference of potential of a predetermined magnitude, said tubular member being axially expandable in response to the heating effect of the current in said gas discharge and means interconnecting said tubular member and said first Contact to make and break said contacts in response to axial movement of said tubular member.

3. In a relay, a base, first and second cooperating contact members, contact support members for supporting said first contact member for movement toward and away from said second contact member, a closed tubular member adapted to function as a first electrode, and insulative base closing one end of said tubular member and a cap closing the other end of said tubular member, a rigid second electrode supported at one end within said tubular member and extending generally parallel to said tubular member intermediate the length of said tubular member, an ionizable lgas within said tubular member, means for applying a difference of potential to said electrode to cause a gas discharge upon the application of a difference of potential of a predetermined magnitude, said tubular member being axially expandable in response to the heating effect of the current in said gas discharge and ymeans interconnecting said tubular member and said first contact member to make and break said contact members in response to axial movement of said tubular member, a flexible strut for supporting said first contact member and extending between the end portion of said rigid member remote from said base and the contact support member for supporting said first contact member and defining an acute angle with each, longitudinal movement of the support member for the first contact member being adapted to flex said strut to move said first contact member toward and away from said second contact member.

4. In a relay, first and second normally open cooperating contacts, means supporting said first contact for movement toward and away from said second contact, a closed tubular member adapted to function as a first electrode, a second electrode within and spaced from said tubular member, an ionizable gas within said tubular member, means for applying a difference of potential to said electrode to cause a gas discharge upon the application of a difference of potential of a predetermined magnitude, said tubular member being axially expandable in response to the heating effect of the current in said gas discharge and means interconnecting said tubular member and said first contact to make and break said contacts in response to axial movement of said tubular member and means for supporting said second contact in a direction toward and away from said first contact in response to ambient temperature changes whereby a substantially constant gap is maintained between said contacts in the absence of gas discharge.

5. In a relay, a support, first and second cooperatlng contacts, means including a flexible normally bowed bendable member for supporting said first contact for movement toward and away from said second contact, a closed tubular member connected at one end to said support and adapted to function as a first electrode, a second electrode within said tubular member, an ionizable gas within said tubular member, means for applying a difference of potential to said electrode to cause a gas discharge upon the application of a difference of potential of a predetermined magnitude, said tubular member being axially expandable in response to the heating effect of the current in said gas discharge and means interconnecting said tubular member and said first contact to make and break said contacts in response to axial movement of said tubular member, said first contact being connected to said bendable member intermediate of its length, said bendable member, in its end connections to said tubular member and said support, being of greater length than the distance between such end connections so as to remain bowed in the absence of gas discharge in said tubular member.

6. In a relay, a support, first and second cooperating contacts, means supporting said first contact for movement toward and away from said second contact, a closed tubular member connected at one end to said support and having one free end and adapted to function as a first electrode, a second electrode within said tubular member, an ionizable gas within said tubular member, means for applying a difference of potential to said electrode to cause a gas discharge upon the application of a difference of potential of a predetermined magnitude, said tubular member being axially expandable in response to the heating effect of the current in said gas discharge and means interconnecting said tubular member and said first contact to make and break said contacts in response to axial movement of said tubular member, a first normally bowed deformable contact support member connected between the free end of said tubular member and said support, a second normally bowed deformable contact support member opposed to said first contact support member and connected between the free end of said tubular member and said support, both of said contact support members being of greater length than the straight line distance between their points of connection to the tubular member and the support in the absence of gas discharge within said tubular member.

References Cited in the file of this patent UNITED STATES PATENTS 1,433,073 Davis Oct. 24, 1922 1,740,202 Ruben Dec. 17, 1929 2,185,433 Fenn et al. Jan. 2, 1940 2,200,443 Dench May 14, 1940 2,232,002 Hays Feb. 18, 1941 2,292,976 Spencer Aug. 11, 1942 2,660,646 Fritzinger Nov. 24, 1953 

